Pounding electro beats filled the cavernous House of Blues Tuesday night as a mostly college-age crowd danced elbow-to-elbow to tunes spun by popular young German disc jockey Zedd. But after the show ended and the lights came on about 12:15 a.m. Wednesday, three people inside were down, apparently from drug overdoses.

Authorities said they might have taken a form of ecstasy known as Molly, a controversial drug that has recently soared in popularity in some cities.

“As always, the safety of our guests is our top priority,” said Jay Anderson, a spokesman for the House of Blues, which is owned by Live Nation. “One individual has unfortunately passed away, and our thoughts go out to their family and friends for their loss. This matter is under investigation, and we are continuing to work with local officials.”

The popular club on Lansdowne Street in Boston’s Fenway voluntarily shut down Wednesday night on the second scheduled night for Zedd.

It was unclear how long the club would stay closed. Dot Joyce, spokeswoman for Mayor Thomas M. Menino, said the Mayor’s Office of Consumer Affairs and Licensing will issue a request for the management to appear at a hearing next week to address what happened.

The House of Blues has been cited by the Licensing Board in the past, according to city records. In Jan. 2010, the board found the business in violation for failing to supervise the line outside the establishment where some patrons were observed inhaling nitrous oxide, a hazardous gas, from a balloon. In April of the same year, the board suspended business there for a day as a penalty for violations that included exits blocked by beer kegs and marijuana use in the green room, where performing bands prepare to go onstage.

In July 2012, at the Comcast Center in Mansfield, a venue owned by Live Nation, a 19-year-old man and 27-year-old man died of a drug and alcohol overdose during a festival there.

Anderson, the spokesman, declined to specify what measures Live Nation takes to prevent drug use at its facilities.

Robert Merner, commander of the Boston Police Department’s Drug Control Unit, said investigators are trying to determine what drug the
victims at the House of Blues took.

“My understanding is that there is a potential that we are talking about Molly,’’ Merner said by phone, referring to the street name for the drug MDMA, a pure form of ecstasy known as the drug of choice at techno or electro music events. He said users typically fall in the 16-24 age range.

“The problem is that it raises body temperature, heartbeat, and causes severe dehydration,” Merner said. “If you decide to choose alcohol over water to quench your thirst while you’re on it, the alcohol leads to dehydration, too, so it increases that problem.”

Merner has not seen a large incidence of the drug, “maybe about 25 or fewer cases in the past three years.”

Authorities are concerned that as the popularity of techno music rises, so, too, will the use of Molly.

Rita Nieves, director of the addictions bureau of the Boston Public Health Commission, said MDMA and ecstasy account for less than 1 percent of overdose cases in the city, with heroin outdistancing any other drug, accounting for almost two-thirds of all overdose cases.

But with college students arriving in Boston in coming days, Nieves said it is important they know of the dangers.

“When you’re in a club and buy something from someone, you really don’t know what you’re putting into your body, and all of a sudden, you’re not in charge anymore,” she said.

Anthony Pettigrew, spokesman for the US Drug Enforcement Administration, said that while deaths from MDMA are rare, much of what is being passed off in clubs as pure is not.

“When people take it, they assume it’s pure, but they don’t know what’s in it,” he said. “We’re talking about stuff that people are manufacturing in their bathtubs. People who use should realize there is no way to know what is in it.”

While Boston might not see the drug extensively, police in Quincy have. Three months ago it suddenly became prevalent, Lieutenant Detective Patrick Glynn said.

“It’s almost becoming epidemic,” said Glynn, who is head of the drug control unit.

Police have made a dozen arrests of people holding capsules or small sandwich bags of Molly, said Detective Brian Coen of the drug control unit.

There were six overdoses in which the symptoms appear to be from the drug, Glynn said. None of the overdoses were fatal. Typically, the drugs are found at clubs or private parties, Glynn said.

“People don’t view it as an extremely dangerous drug,” he said. “It’s all word of mouth on the street: ‘Hey, this is better than ecstasy because this is pure ecstasy.’ People who are curious and want to experience something new begin to overdose on it, because they use too much. It’s very dangerous.”

Coen described Molly as a party drug that often comes in a white powder or that can look like colorful rock candy. Club and party goers use the drug to enhance the effects of dancing to the techno music typically associated with raves.

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